Broadly, lymphoma is distinguished from leukaemia in its clinical presentation, where lymphoma predominately involves lymph nodes, and leukaemia the blood and bone marrow, and by the fact that lymphomas arise from cells that reside in the lymphatic system rather than in the bone marrow. However, in the context of the cell of origin this is perhaps a rather nebulous distinction, and there is evidence that chronic lymphocytic leukaemia (CLL) may emerge in differentiated/mature lymphocytes in the periphery
[!INFO] The correct identification of AML vs ALL is veryimportant as a determines treatment.
| AML | ALL |
|---|---|
| Diverse Group of diseases | |
| Proliferation of myeloid blasts | Lymphoid blasts |
| clonal proliferation of myeloid precursors with a reduced capacity to differentiate into more mature cellular elements. | |
| As a result, there is an accumulation of leukemic blasts or immature forms in the bone marrow, peripheral blood NCNC anaemia, ⬇ Platelets |
Blasts infiltrate bone marrow NCNC anaemia, ⬇ Platelets |
| Symptoms: pancytopaenic symptoms: anemia, bleeding, and an increased risk of infection. Bone pain is uncommon; Fever = Infection! | Similar Bone pain can be presenting complaint in children (and adults)? |
| CNV involvement less | CNS invovelemt more common |
| No / Less lymphadenopathy | Lymphadenopathy more predominant |
| Presentation as Tissue mass is less common | Can present as thymic or testicular masses |
| Gum hypertrophy, Skin involvement and CNS disease occur in myelomonocytic and monocytic types | |
| Commonest adult acute leukemia (80% of cases) - 65 years | Occurs in children. |
| Accounst for only 10% of paediatric leukemia | |
| About 1.5x commoner in males | |
| De novo OR in backdrop of preexisting myelodysplasia OR cytotoxic medication | Acquired mutations leading to formation of BCR-ABL fusion gene (among others) (via 9;22 translocation) |
| Assoc. with trisomy 21; Fanconi anemia; | |
| Auer rods seen | Auer rods never seen. |
| Myeloblast have finer chromatin and more cytoplasm. Cells are peroxidase positive. |
Lymphoblasts have course chromatin Cells are PAS positive |
| negative. | Immunophenotyping: Terminal deoxynucleotidyl trasnferase (TdT) positive |
| Increased risk of DIC (in promyelocytic variant) | Increased risk of Tumour lysis syndrome |
| "devastating"; poor prognosis | Good prognosis (esp in t(12:21)) |
| Good prognosis: t[8:21], inv[16] |
bad prognosis: Presence of MLL rearrangements, Presence of BCR-ABL fusion gene t(9:22), t(4:11), hypoploidy |
- Aggressive cancers
- Child with lymphocytosis must be evaluated. Hepatosplenomegaly, complaining of bone pain / limp are red flag signs!
- investigations focus on identifying haematologic malignancy and then identifying the type of malignancy (myeloid or lymphoid, subtypes of lymhpoid etc)
Note : T cells are the commonest type of lymphocytes in healthy states, followed by B and NK cells.
| EBV / mononucleosis | ALL |
|---|---|
| Teens | 4 year olds |
| Atypical lymphocytes | Blast cells |
| Acute disease course | Acute disease course |
| Splenomegaly and lymphadenopathy | hepatosplenomegaly and lymphadenopathy |
| Lymphocytosis | Lymphocytotis with anaemia and thrombocytopaenia |
| Not present | Clinical feature of cell line suppression including mucosal bleeds |
| Several long term complications: lymphoma, multiple sclerosis, chronic EBV infection, nasopharyngeal CA and others | |
| Very high WBC indicates ALL (but WBC can be low or normal in ALL) |